1. Field of the Invention
The present invention relates generally to tennis. More particularly, the present invention concerns weighted tennis training devices. Even more particularly, the present invention concerns weighted tennis-swing training devices.
2. Prior Art
In the above referred to co-pending application and issued patent, there is disclosed a locking device which may be removably secured about a shaft. The device is defined by interdigitated opposingly arranged body portions that are locked together by way of a helically threaded fastener. The body portions cooperate to define a body member having a central aperture formed therethrough, which enables the device to be secured to the shaft.
It has now been discovered that the principles embodied in the locking device thereof may be used to provide training devices to improve a player""s tennis swing. It is to this to which the present invention is directed.
In accordance with the present invention there is provided a training device for improving a player""s tennis swing. According to this aspect, the tennis-swing training device generally, comprises:
(a) a racket, said racket comprising a stringed head having a lower end portion, a handle having an upper end portion, and a pair of beams connecting the head to the handle and defining an open area between the upper and lower end portions thereof;
(b) a shaft having a first end and a second end and a medial portion between the ends of the shaft;
(c) means for mounting the shaft to the racket whereby the first end is proximate to the upper end portion of the handle, the second end is proximate to the lower end portion of the head, and the medial portion is proximate to the open area; and
(d) means movably mounted on the medial portion of the shaft and positionable in the open area for changing the balance and the resultant center of gravity of the tennis racket, wherein said means movably mounted on the medial portion of said shaft comprises a weight mounted for movement in the opening between the head and handle portions, the weight comprising:
(1) first and second interdigitating opposedly arranged body portions; and
(2) at least one locking member for locking the first and second body portions together and securing the body portions to the shaft thereby precluding the slidable movement of the shaft relative to the body member.
At least one of the two body portions of the weight has a threaded channel formed therein so that when the two body portions are interdigitated about the shaft, the resulting body member has a channel drawn from its outer surface to its inner surface.
The locking member, which may be a screw or the like, fits into the channel and functions to secure the two body portions together, while allowing the shaft to slidably move through the central aperture when not engaged therewith.
When fitted together, the threaded screw secures the body member to the shaft in position by pressing the shaft against the inner surface of the body member. The body member is now in a fully locked position. In the fully locked position, the body member is restricted from slidable movement along the bottom portion of the shaft. The body member does not move relative to any portion of the shaft. The body member has a sufficient weight or mass such that in executing a tennis swing the centripetal force created thereby forces a proper swing.
The tennis-swing shaft, preferably, is disposed in part in the area formed between the head and the rim of the racket to position one or more weights, of the same, or different mass, or as desired, either closer to the rim or closer to the head to provide a tennis swing practice or warm-up weight. If desired, the shaft may be tapered.
The tennis-swing shaft may have a generally smooth exterior surface, or provided with a series of recesses and/or detents, or threaded. The weight and screw-like locking member, described hereinabove, would be locked to the shaft provided with the screw-like member engaging the smooth exterior surface or interlocking with one the detents.
In a preferred embodiment according to this invention, the shaft comprises a generally hollow cylindrical tube, the tube being open at one end and internally threaded whereby to receive and threadably engage with a threaded stem, a first U-shaped bracket fixedly disposed on the stem and adapted to engage with the handle, and a second U-shaped bracket rotatably mounted to the other end of the tube and adapted to engage with the rim. The shaft could be positioned such that the rotatable bracket engages with the handle. Rotation of the stem relative to the cylinder in first and second opposite directions, respectively, causes the brackets to move axially away from one another and into engagement with the tennis bracket handle and head, and towards one another and from engagement with the racket and be removed therefrom, if desired.
Additionally, the weight could be, preferably, generally cylindrically shaped and have a central bore for fitment to the shaft, such as the weight having the opposed interdigitating body portions as described hereinabove.
In one arrangement, the cylindrically shaped weight is integrally formed and the wall of the central bore provided with thread to threadably engage with the exteriorly threaded shaft. Additionally, in another arrangement, the cylindrically shaped weight includes a hollow extending radially between the central bore and outer periphery of the weight and within which is mounted a spring biased locking member, the locking member having an inward end being biased radially inwardly to engage a selected detent.
The mounting of the shaft to the tennis racket preferably aligns the axis of the shaft so as to be generally coaxially aligned with the axis through the handle (and through the geometric center) of the racket.
In one preferred embodiment, described hereinabove, the mounting arrangement comprises the opposed pair of U-shaped mounting brackets that are moved towards or away from one another, depending on the rotation of the shaft portions.
In another preferred embodiment, the mounting arrangement comprises first and second pin members, each located at one and the other respective end of the shaft and spring biased for movement between a first position outwardly of the shaft end and a second position retracted inwardly of the shaft end, and first and second detents, the first detent being located in the handle for receiving the first pin and the second detent being located in the head for receiving the second pin.